How to offset bezier curve?
Someone will tell if I'm wrong but it looks like there's no easy way to do it. In this question they talk about an Offset Tool but I don't find it.

You could do it this way, but at the end you will need to convert your curve to mesh:


Select your curve, go in the Properties panel > Geometry.
Play with the Extrude value.
Duplicate your curve with shift D and Enter.
Play with the Offset value of your second curve.
Convert your curve to mesh with alt C.
If you decide to come back to curve, again alt C. As you will have a lot of vertices you can use the Simplify Curves addon (play with the values on the bottom of the T panel).


You could also directly convert your curve to mesh, then extrude your mesh on the Z axis, and alt S (shrink) the shape. Then convert back to curve if you need, and again, use the Simplify Curves addon if you want to limit the amount of vertices.